I have a confession... I am a developer, a true developer. I am infrastructure illiterate, meaning I very, very, very infrequently (like maybe twice ever) install a domain controller by myself. I don't assign IP addresses, heck it's rare that I install Windows Server from scratch (we use network installs internally, I don't even have to think).
For demos, I usually just download a VHD that someone else built, and usually that VHD is a Windows Server OS that is a domain controller with lots of other stuff installed on it. Self-contained, sure, but this time I needed a separate domain controller. Time for me to get out of my comfort zone.
Thank goodness this has been written up and blogged on by many, many people. I don't even need to provide screen shots of anything here, just a few links and you can create your own VHD that is a domain controller for use with your other VHDs. Sweet.
I did vary a few things from those walkthroughs. For instance, I used the IP address 192.168.0.1 for my domain controller, and didn't install WINS. Other than that, just follow along the steps in the above articles and it couldn't be simpler.